In the fabrication of lightweight plastic bottles, e.g., high density polyethylene bottles in half and 1 gallon dairy types, problems are frequently encountered by the presence of pin holes, cuts, tears, weaknesses or malformities in the container structure. The exact cause of the fault may be any one or a combination of causes including malfunction of the blow molding machine and contamination of the resin used to fabricate the bottles.
If a faulty container were filled with a liquid product, such as milk, then the product would be lost. This results in higher production costs based upon the value of the product lost, the value of the operating time lost in filling the faulty container; and the value of polymer used in fabricating the bottle.
In recognition of these problems, lightweight containers are generally tested for integrity prior to their filling with product. Unfortunately, the testing devices presently available are generally of a differential pressure type designed for testing high strength containers, such as glass bottles or cans, and are not suitable for lightweight plastic because they deform the plastic bottle and provide inaccurate and unreliable test results.